A goal of the present invention is to provide an ad hoc network-autonomous wireless location system (NAWLS) capable identifying and locating mobile devices. These network autonomous systems will preferably be used for law enforcement and disaster recovery purposes to acquire the MS identifiers, such as the TMSI, IMEI, and IMSI (i.e., the Temporary Mobile Subscriber Identity, International Mobile Station Equipment Identity, and International Mobile Subscriber Identity, respectively), and to locate the identified mobile devices. The subject matter of the present application relates to various systems in the wireless location and other related fields. This “background art” is briefly summarized below.
Network-Based Wireless Location Systems
Network-based wireless location systems (WLS) have in the past been deployed either as overlay networks or integrated into the wireless network infrastructure. These “in-network” solutions allow for location determination and wide area surveillance of mobile devices in commercial wireless networks. While “in-network” solutions offer powerful intelligence and law enforcement capability, it is not always possible to have a hard-wired connection to the networks of interest because the wireless networks use incompatible signaling transport, lack the requisite triggering-tasking-provisioning interface(s), or are simply non-cooperative. However, many of the location capabilities of “in-network” location solutions can be obtained without a hardwired connection to the wireless network(s) of interest.
One example of an early network-based WLS is described in U.S. Pat. No. 5,327,144, “Cellular Telephone Location System,” Jul. 5, 1994. This TruePosition Inc. patent describes a cellular telephone location system for recording the location of one or more mobile cellular telephones. The disclosed system comprises three or more cell site systems, each located at a cell site of a cellular telephone system. Each cell site system includes an antenna that may be mounted on the same tower or building as the antenna employed by the cellular telephone system and equipment that may be housed in the equipment enclosure of the corresponding cell site. The cell site systems are coupled via T1 communication links to a central site. The central site may be collocated with the cellular telephone system's MTSO. The central site is further coupled to a database, which may be remotely located from the central site and made available to subscribers.
Another even earlier example is described in U.S. Pat. No. 4,728,959, “Direction Finding Localization System,” Mar. 1, 1988 owned by the applicant. This patent describes a system combining the relative insensitivity of phase angle differences of a radio signal to the signal distortions inherent in an urban environment with digital signal processing techniques to produce an accurate and economical way to locate a mobile telephone in a cellular telephone network. Phase angle measurements indicative of the angle of direction of a mobile transmitter station from each of a plurality of land stations are obtained and are processed to produce a probability density function. The probability density functions are combined to produce an area of uncertainty representing the position of the mobile transmitter station.
Wireless Location System with Mobile LMU
Published patent application US20080158059A1, “Portable, Iterative Geolocation of RF Emitters,” filed Dec. 27, 2006, owned by TruePosition Inc., discloses that iterative geolocation of a stationary RF emitter through the use of TDOA may include the use of a single portable geolocation sensor, a pair of portable geolocation sensors and three or more portable geolocation sensors. Adding portable geolocation sensors to the iterative process reduces the constraints on the signals to be located as well as providing a reduction in the number of iterations required to obtain improved location accuracy.
Advanced Triggers and Geo-Fencing
Published patent application US20060030333A1, “Geo-fencing in a Wireless Location System,” filed Aug. 8, 2005, owned by TruePosition Inc., discloses methods employed by a WLS for locating a wireless device operating in a geographic area served by a wireless communications system. An exemplary method includes defining a geo-fenced area. The method then includes monitoring a set of predefined signaling links of the wireless communications system, and detecting that a mobile device has performed any of the following acts with respect to the geo-fenced area: (1) entered the geo-fenced area, (2) exited the geo-fenced area, and (3) come within a predefined degree of proximity near the geo-fenced area. A high-accuracy location function may then be triggered in order to determine the geographic location of the mobile device. In this application, the approach of changing the beacon settings of the operator network is described as a way to create geo-fenced areas for detection and localization of GSM and UMTS mobiles. Fundamentally, locating a mobile transmitter with networked receiver technology does not require a physical/wired connection with the network. As long as the geographically distributed receiver(s) can determine their own three-dimensional position, and their own three-dimensional velocity, if moving, while they are acquiring and collecting the signal of interest (SOI), then the transmitting mobile device(s) can be located. Thus, a network autonomous architecture of the kind described herein below offers the convenience of a “wireless only” connection to the network(s) of interest as well as the secondary advantage of portable and mobile operation since a hard-wired network connection is not required. The price to pay for this convenience is additional hardware and software compared to an in-network wireless location solution.
Published patent application US20060003775A1, “Advanced Triggers for Location-based Service Applications in a Wireless Location System,” filed Jun. 10, 2005, owned by TruePosition Inc., discloses an exemplary method including monitoring a set of signaling links of a wireless communications system, and detecting at least one predefined signaling transaction occurring on at least one of the predefined signaling links. Then, in response to the detection of the at least one predefined network transaction, at least one predefined location service is triggered.
Automated Configuration using Downlink Receivers
Published patent application US20080132247A1, “System For Automatically Determining Cell Transmitter Parameters To Facilitate The Location Of Wireless Devices,” filed Dec. 1, 2006, owned by TruePosition Inc., describes techniques for locating wireless devices involving the MS making measurements of the signals transmitted by geographically distributed base stations within a wireless network. If some key site information is known about these transmitters, such as the transmitter location, transmit signal power, signal propagation, and transmit signal timing, measurements of these transmit signals by a MS can be used to determine the position of the MS. An automatic method to detect transmitters, identify key transmitter information, and utilize the base station transmit signals to perform location is presented. In addition, this system facilitates the use of cell site transmit signals that are part of multiple wireless networks.
Published patent application US20080132244A1, “Subscriptionless Location Of Wireless Devices,” filed Dec. 27, 2006, owned by TruePosition Inc., describes wireless location techniques involving a wireless device making measurements of signals transmitted by geographically distributed base stations within a wireless network. If some key site information is known about these transmitters, such as the transmitter location, transmit signal power, signal propagation, and transmit signal timing, measurements of these transmit signals by a device to be located can be used to determine the position of the device. In this example, all information exchange between the device and the location node is facilitated by a data link that is not provided by the wireless network providing signals used in the location estimation process. Accordingly, devices may be located based on downlink signal measurements made by the devices, where the devices are not part of the wireless network, are not provided wireless service by the network, and do not possess the ability to transmit signals to the wireless network, and where communication resources of the wireless network are not consumed to facilitate location.
IMSI Catcher
European Patent EP1051053 “Method For Identifying A Mobile Phone User Or For Eavesdropping On Outgoing Calls,” Frick et al., published Sep. 7, 2003, discloses a method for identifying a MS in a GSM radio communications network using a virtual base transceiver station (VBTS) and an instrumented test mobile telephone. The method requires the VBTS and a test mobile be in close proximity with the target mobile to acquire the same broadcast channel (BCCH) information as the target mobile. The VBTS uses the acquired BCCH information to emulate a BTS other than the one presently serving the MS. The MS, detecting a new higher power beacon with a new Location Area Code (LAC), then executes a Location Update to the VBTS, allowing the pre-existing TMSI, IMEI, and IMSI to be collected.
U.S. patent application Ser. No. 11/996,230, “Acquiring Identity Parameters by Emulating Base Stations,” Pridmore et al., filed Jul. 17, 2006, discloses a method to acquire the identity (pre-existing TMSI, IMEI, MS-ISDN and IMSI) of multiple GSM or dual-mode GSM/UMTS devices by emulating multiple base stations.
While the above described methods and systems allow for the collection of identities of mobile devices, a wide-area system suitable for identifying and locating GSM or dual-mode GSM/UMTS devices while intelligently minimizing the disruption of the local wireless communications network is not disclosed. While the system described in EP1051053 may possess a location of the interrogated mobile due to the need for close proximity to the interrogated MS, the system in application Ser. No. 11/996,230 (Pridmore et al) widens the coverage area to a multi-cell area, increasing the effects of interference, but then cannot locate the interrogated MS more precisely than the cell/sector level; i.e., the system does not appear to be able to locate the MS more precisely than the GSM Cell Global Identifier (CGI) or UMTS Cell Identity (CI) level.
As mentioned above, it would be advantageous to law enforcement and disaster rescue personnel to have access to an ad hoc network-autonomous wireless location system (NAWLS) capable of quickly identifying and locating mobile devices without co-operation of the local wireless network operators. Such a system will preferably use standardized radio messaging, without further connection to the underlying radio network, to acquire the MS identifiers, such as the TMSI, IMEI, MS-ISDN and IMSI,. The present application describes a system achieving these goals.